The restoration of dental structures, including caries, decayed dentin, or decayed enamel, is often accomplished by the sequential application of a dental adhesive followed by a dental material (e.g., a restorative material) to the relevant dental structures. Similarly, adhesives are also used in the bonding of dental materials (e.g., orthodontic appliances, generally utilizing an orthodontic adhesive) to a dental structure. Often various pretreatment processes are used to promote the bonding of dental adhesives to dentin or enamel. Typically, such pretreatment steps include etching using, for example, inorganic or organic acids, followed by priming to improve the bonding between the tooth structure and the overlying adhesive.
Whether for application of dental restoratives (e.g., cured or uncured composites such as glass ionomer cements, modified glass ionomer cements, etc.; fillings; sealants; inlays; onlays; crowns; bridges; etc.) or orthodontic appliances to a dental structure surface, the etchants, primers, and adhesives are typically applied in a step-wise fashion. Often between such steps, one or more rinsing and drying steps are used. As a result, dental restoration and the application of orthodontic appliances typically involve multi-step procedures.
In order to reduce the complexity, difficulty, and time required to perform such procedures, recent efforts have been made to combine two or more of these steps together in a single step by providing compositions that perform multiple functions. For example, efforts have been made to develop self-etching adhesives, i.e., adhesive compositions in which a single composition is able to perform the etching, priming, and adhesive functions in a single step. One of the problems associated with the development of suitable self-etching adhesive formulations is that the combinations of components typically used in such compositions are not always stable, which can lead to reduced shelf life of the composition. Consequently, there is a need for a means to provide self-etching adhesive compositions that have sufficient stability and shelf life to be useful in the typical dental and/or orthodontic practice.